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Road Dynamics

  • Reza N. Jazar
Chapter

Abstract

Passenger cars are developed to move on smooth paved pre-designed roads. To keep vehicles on road, we need a steering mechanism to provide steer angle as an input to the vehicle dynamic system. Ideally, all wheels of a vehicle should be able to steer independently such that the vehicle follows the desired path at the given speed. In this chapter we review steer and road dynamics.

Roads are made by continuously connecting straight and circular paths by proper transition turning sections. Having a continuous and well-behaved curvature is a necessary criterion in road design. The clothoid spiral is the best smooth transition connecting curve in road design which is expressed by parametric equations called Fresnel Integrals. The curvature of the clothoid curve varies linearly with arc length and this linearity makes clothoid the smoothest driving transition curve. Having a road with linearly increasing curvature is equivalent to entering the path with a steering wheel at the neutral position and turning the steering wheel with a constant angular velocity. This is a desirable and natural driving action.

Ideally, perpendicular lines to all wheels of a vehicle intersect at a single point called the kinematic center of rotation. When a vehicle is moving very slowly, we may assume the velocity vector of each wheel is in their tire plane. Therefore, the perpendicular lines to the tire planes intersect at the kinematic center of rotation of the vehicle, somewhere on the rear axis. However, when the vehicle moves faster, the actual center of rotation will move away from the kinematic center of rotation. Steering mechanism relates the last and right steerable wheels and provide a mathematical relationship to calculate all steer angles based on the angle of the steering wheel or the steer angle one of the wheels.

Keywords

Road dynamics Road design Steering mechanism Steering dynamics Clothoid Autodriver Four-wheel steering 

References

  1. Bourmistrova, A., Simic, M., Hoseinnezhad, R., & Jazar, R. N. (2011). Autodriver algorithm. Journal of Systemics, Cybernetics and Informatics, 9(1), 56–66.Google Scholar
  2. Genta, G. (2007). Motor vehicle dynamics, modeling and simulation. Singapore: World Scientific.zbMATHGoogle Scholar
  3. Hunt, K. H. (1978). Kinematic geometry of mechanisms. London: Oxford University Press.zbMATHGoogle Scholar
  4. Jazar, R. N. (2010b). Mathematical theory of autodriver for autonomous vehicles. Journal of Vibration and Control, 16(2), 253–279.MathSciNetCrossRefGoogle Scholar
  5. Jazar, R. N. (2011). Advanced dynamics: Rigid body, multibody, and aerospace applications. New York: Wiley.CrossRefGoogle Scholar
  6. Jazar, R. N. (2012). Derivative and coordinate frames. Journal of Nonlinear Engineering, 1(1), 25–34.  https://doi.org/10.1515/nleng-2012-0001 Google Scholar
  7. Jazar, R. N., Subic A., & Zhong N. (2012). Kinematics of a smart variable caster mechanism for a vehicle steerable wheel. Vehicle System Dynamics, 50(12), 1861–1875.CrossRefGoogle Scholar
  8. Jazar, R. N. (2017). Vehicle dynamics: Theory and application (3rd ed.). New York: Springer.CrossRefGoogle Scholar
  9. Marzbani, H., Simic, M., Fard, M., & Jazar, R.N. (2015). Better road design for autonomous vehicles using clothoids. In E. Damiani, R. Howlett, L. Jain, L. Gallo & G. De Pietro (Eds.), Intelligent interactive multimedia systems and services. Smart innovation, systems and technologies (Vol. 40). Cham: Springer.Google Scholar
  10. Soni, A. H. (1974). Mechanism synthesis and analysis. New York: McGraw-Hill.Google Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Reza N. Jazar
    • 1
  1. 1.Aerospace, Mechanical and Manufacturing EngineeringRMIT UniversityMelbourneAustralia

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